Shaver with roller guided drive



March 1965 w. MESSINGER ETAL 3,172,201

SHAVER WITH ROLLER GUIDED DRIVE Filed July 15, 1963 2 Sheets-Sheet 1 1Fig.1

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Rosem- \JICJI March 1965 w. MESSINGER ETAL 3,172,201

SHAVER WITH ROLLER GUIDED DRIVE Filed July 15, 1963 2 Sheets-Sheet 2Fig. 3

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ATTORNEYS United States Patent C) 3,17 2,201 SHAVER WITH ROLLER GUDEDDRIVE Werner Messiuger and Robert Wicli, Frankfurt am Main,

Germany, assignors to Braun Aktiengeselischaft, Frankfurt am Main,Germany, a German company Filed July 15, 1963, Ser. No. 295,102

Claims priority, application Germany, Huly 18, 1962,

Claims. (6!. -4332) This invention relates in general to power-drivenshavers, and in particular to a new and useful power-driven shaverhaving a stationary cutter which partially envelopes a reciprocatingmovable cutter which movable cutter is driven by means of a slide whichoscillates on roller bearings.

The present invention has particular application to a power-driven dryshaver of a type which employs a freely flexible, perforated head plateor foil which serves as a stationary cutter and which overlies areciprocating movable cutter in the form of a knife block. Theperforated head plate has a configuration conformable to the movableknife block or cutter, and the cutter is urged against the inner surfaceof the head plate by spring means as it is reciprocated. The knife blockis advantageously connected or coupled with a driving member, such as arocker arm or an eccentric, through a universal joint or Cardan joint.In dry shavers of this type the knife block is reciprocated relative tothe stationary foil, either directly by a rocker arm or eccentric drivenby the motor, or

by means of an intermediate element which permits the knife block toperform a limited Cardanic movement. In some instances the knife blockis urged against the stationary foil or cutter head by means of springsand is moved by means of a slide member which is biased by the spring toprovide a constant and sung engagement over the entire operating strokeof the knife block. In arranging the springs on the slide member and indimensioning the springs with regard to the required contact pressure,consideration must be given to the fact that the springs, in the courseof the reciprocating movement of the knife block, assume their mostrelaxed or extended position at each end of the knife block stroke,while the springs are most compressed in the center position of theknife block stroke. When helical or coil springs are employed, not onlyare they stressed in regard to tension and pressure, but also in respectto twisting or bending.

Thus, with prior art constructions springs must be selected withsufficient strength to prevent movement of the knife block away from theperforated foil, particularly at the end positions of the movement ofthe knife blocks. This is so because shavers of this type require, forefiicient cutting action, that the active portions of the movable andstationary cutters be maintained in exceedingly close and preciseengagement throughout the area of cut and in all positions of themovable cutters throughout their stroke.

With the above in mind it can be seen that in the center position of theknife block the pressure or contact force generated by the springs islarger than is actually required. This, of course, unnecessarilyincreases the friction between the cooperating cutter portions andrequires not only greater energy to move the cutter elements relatively,but also increases the wear on the knife edges and on the inner surfaceof the stationary cutting foil.

In accordance with another known dry shaver, the knife block is drivenby a motor through a rocker arm and the slide member, so that theinterposed spring is not deformed during the working stroke. In such aknown embodiment the slide member is mounted on a swing arm in themanner of an articulated quadrangle, so that the swinging takes placenot only backwardly and forwardly in the cutting direction, but alsoperpendicularly thereto. In this manner 3,172,201 Patented Mar. 9, 1965'ice the slide member stresses the spring periodically only. However,such a construction does not overcome the disadvantage that the pressureand contact force exerted by the springs is larger in the centerposition of the knife block than is actually required.

With another known construction a spring is arranged to bear against theslide which is guided exactly parallel to the movement of the knifeblock, and the superimposed knife block and slide members are jointlydriven by the rocker arm from the motor so that the helical springassumes a slanted or oblique position when the knife block has reachedthe extreme positions of its stroke. With a construction of this naturethe spring is alternately bent toward one side or the other and theaforementioned disadvantages are also present.

In accordance with the present invention there is provided a drivingarrangementbetween the motor and the knife block which is free of thedisadvantages of the prior art constructions, and which arrangementincludes springs oriented to provide uniform contact pressure betweenthe movable and stationary cutters throughout the entire length of thestroke of the movable cutter. In accordance with a preferred embodimenta slide member is mounted on rollers between two parallel surfaces ofthe casing of the shaver and is imparted with a back and forth movementwhile it is guided in a parallel manner by the rollers. The slide memberis connected, by a bolt member, to the movable cutter by a connectionpermitting pivotal movement of the cutter. By means of the inventivearrangement, the springs uniformly stress the movable cutter throughoutits entire stroke, and the pressure or contact force exerted by thespring can be dimensioned so as to always maintain an optimum contactpressure. With the invention the maximum hearing or contact pressurerequired for the spring is thus much smaller than in the prior artconstructions. The friction which takes place in the mounting of theslide member is comparatively small relative to the gain in friction inthe cutting system, and for this reason this additional friction can bedisregarded in computing the required force of the spring.

In one embodiment the slide member is mounted so that on each side ofthe driving connection one surface of the slide member is guided by twoguide tracks formed by the rollers, arid the other side is guided by asingle guide track formed by the rollers. These guide tracks arearranged in a special manner in the form of a three-point mounting inthe plane of movement of the knife block, or in a plane which isparallel to the plane of movement of the knife block. The lower guidesurface is advantageously provided at a plate member which is urgedagainst the slide by the pressure of a supporting spring.

Accordingly it is an object of the invention to provide an improved dryshaver construction.

A further object of the invention is to provide a dry shaver whichincludes a driving motor for reciprocating a knife block which isenveloped by a stationary cutting head and wherein the drivingconnection between the motor and the knife block includes a slide whichis supported and guided on roller bearings for parallel to and fromovement.

A further object of the invention is to provide a powerdriven dry shaverwhich includes a reciprocating cutting member in the form of a knifeblock which is urged by spring means against the inner surface of astationary cutter in the form of a perforated, flexible foil, and whichincludes a driving electric motor arranged to move a slide, which isconnected to the knife block, baekwardly and forwardly, the slide beingguided by roller bearings for parallel back and forth movement.

A further object of the invention is to provide a powerdriven dry shaverwhich is simple in design, rugged in construction and economical tomanufacture.

.tion.

7 stroke.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specifica- For a better understanding of the invention, itsoperating advantages and specific objects attained by its use, referenceshould be had to the accompanying drawings and descriptive matter inwhich there are illustrated and described preferred embodiments of theinvention.

In the drawings:

FIG. 1 is a partial transverse section through the upper portion of adry shaver constructed in accordance with the invention, the sectionbeing taken along line 11 of FIG. 2;

FIG. 2 is a longitudinal section of the shaver indicated in FIG. 1; and

FIG. 3 is a side view of the shaver. Referring to the drawings inparticular, the invention embodied therein comprises a power-driven dryshaver having a reciprocating movable cutter or knife block generallydesignated 1.

inafter.

The upper portion of the casing 5 is covered by a cap or cover memberwhich is releasably secured thereto.

The cap 10 is provided with an opening 32 to permit passage of thespring 2 which is mounted on the slide member 6, and to also permitpassage of a driving bolt member '7 which is secured to the slidemember. A substantially U-shaped bearing member or yoke 29 is rotatablymounted on the bolt 7 and is held downwardly -to compress the spring 2by means of a disc or washer 19. The bearing'member 20 has spaced armportions 20a and Ztib which rotatably carry a pin 21 which is connectedat each of its ends to the knife block .1 in a manner permitting theknife block to pivot slightly about the axis of the pin. The slide 6 hasa fork-shaped'lower portion 8 forming an elongated slot 8a into whichextends an eccentric pin l which is carried on the end of a drive memberor shaft 9. in some instances a rocker arm is employed instead of aneccentric pin 23 for driving the slide 6.

In accordance with the invention the slide 6 is mounted in a manner topermit its'guiding movement for transmitting a driving motion to thecutting block it with'a minimum offriction during the course of'itscomplete At the upper inner surface or bearing surface 11 of the cap 10there are provided grooves 12 which form guides for upper bearing balls13. The balls 13 are carried in the grooves 12 and similar groovesformed in an upper surface 6a of the slide 6. The slide 6 bearsdownwardly on balls 14 which are carried in comple- -mentary grooves 15formed in the lower surface 6b of the slide 6 and the upper surface orbearing member 16 :of a plate member 17. The plate member 17 is advan.side of the plate member 17 and is supported on the casing 5. Thespring 18, while not absolutely essential since the plate 17 could bemounted directly on the casing 5, provides for compensating for anybearing play of the balls 13 and 14.

vantageously arranged symmetrically to the plane of movement, so that ateach end of the slide there is formed a three-point mounting, that is,one at the bottom and two on top. Of course, the arrangement can beadvantageously reversed so that there would be two balls on the bottomand one on the top of each side of the slide 6.

When the motor 22 runs to rotate the drive member or shaft 9, the slide6 is reciprocated between the two bearing surfaces 11 and 16 anduniformly moves the knife block 1 by means of the bolt 7 backwardly andforwardly. Since the spring 2 bears upwardly on the knife block 1 anddownwardly on the slide which is guided exactly parallel to the knifeblock, the spring is constantly and uniformly stressed and is notsubject to any bearing stresses and hence will not be subject to anypressure, bending or twisting.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. A power-driven shaver construction comprising a housing, a stationarycutter mounted on said housing, a movable cutter block movable incooperative engagement with said stationary cutter, means biasing saidmovable cutter block against said stationary cutter, a driving memher insaid housing, a movable slide connected to said driving member formovement thereby and connected to said movable cutter block to move saidcutter block, said housing including a first member extending above saidslide, .a plate member located below said slide, and roller meanscarried by said plate member and said first member sup- 7 porting saidslide for movement.

In order to insure that the slide is guided during its 7 '61; in theexample illustrated), and four balls all designated 13 are provided onthe opposite side of the slide 6 (the upper face-6a, as illustrated).The halls are ad- 2. A power-driven shaver according to claim 1, whereinsaid roller means includes at least two rollers on each side of thecenter line of said slide bearing against one side of said slide, andone roller bearing against the opposite side of said slide.

3. A power-driven shaver comprising a housing, a stationary cutter inthe form of a perforated flexible foil mounted on said housing, amovable cutter block -movable in cooperative engagement with saidstationary cutter, a driving member, a movable slide connected to saiddriving member for movement thereby and connected to said movable cutterto move said cutter, means carried by said porting said plate member onsaid housing.

4. A power-driven shaver comprising a housing, a stationary cutter inthe form of a perforated flexible foil mounted on said housing, amovable cutter block movable in cooperative engagement with saidstationary cutter, a driving member, a movable slide connected to saiddriving member for movement thereby and connected to said movable cutterto move said cutter, means carried by said slide .to bias said movablecutter blocks against said stationary cutter, roller'means supportingsaid slide for substantially coplanar movement in said housing, theconnectionbetween said slide and said movable cutter block including anupstanding bolt, a yoke member pivotally mounted on said bolt, and abearing pin rotatably supported on said yoke member and connected ateach end t said movable cutterblock.

V 5. A power-driven shaver comprising a housing, a stationary cuttermounted on said housing, a movable cutter block movable incooperativeengagement with said stationary cutter, a driving member in saidhousing, a movable slide connectedto said driving member for mov mentthereby, a boltprojecting fromsaid slide member,

5 6 said cutter block being mounted on said belt for move- 2,536,01512/50 Konrad 30 43.6 ment axially of the latter towards and away fromsaid 2,819,518 1/58 Lussier 3034.1 stationary cutter, spring meanscarried by said slide mem- 2,952,908 9/60 Starre et a1. 30-43.5 her tobias said cutter block towards said stationary cut- 3,045,246 7/62Akerib 30-4392 ter, said housing including a first member extendingabove 5 3,105,298 10/63 C-arissimi 30-4392 said slide, a plate memberlocated below said slide, and FOREIGN PATENTS roller means carried bysaid plate member and said first member supporting said slide formovement. 1,145958 6/59 Germany- 628,599 9/49 Great Britain. ReferencesCited by the Examiner 10 857,095 12/60 Great Britain.

UNITED STATES PATENTS WILLIAM FELDMAN, Primary Examiner.

2,440,114 4/48 Page 3043.3 MYRON C. KRUSE, Examiner.

1. A POWER-DRIVEN SHAVER CONSTRUCTION COMPRISING A HOUSING, A STATIONARYCUTTER MOUNTED ON SAID HOUSING, A MOVABLE CUTTER BLOCK MOVABLE INCOOPERATIVE ENGAGEMENT WITH SAID STATIONARY CUTTER, MEANS BIASING SAIDMOVABLE CUTTER BLOCK AGAINST SAID STATIONARY CUTTER, A DRIVING MEMBER INSAID HOUSING, A MOVABLE SLIDE CONNECTED TO SAID DRIVING MEMBER FORMOVEMENT THEREBY AND CONNECTED TO SAID MOVABLE CUTTER BLOCK TO MOVE SAIDCUTTER BLOCK, SAID HOUSING INCLUDING A FIRST MEMBER EXTENDING ABOVE SAIDSLIDE, A PLATE MEMBER LOCATED BELOW SAID SLIDE, AND ROLLER MEANS CARRIEDBY SAID PLATE MEMBER AND SAID FIRST MEMBER SUPPORTING SAID SLIDE FORMOVEMENT.